animals

[grandh01]

In a certain animal population, for
each of the first 3 months of life, the
probability that an animal will die
during that month is
1/10 . For a group
of 200 newborn members of the
population, approximately how many
would be expected to survive the first
3 months of life?
(A) 140
(B) 146
(C) 152
(D) 162
(E) 170

[truplayer256]

Note that for each month of life, the animal population has a 90% chance of living. Therefore, the number of animals expected to survive the first 3 months of life is:

200(0.9)^3 = 200(81*9)/(1000) = (81*9)/5 => ((80 + 1)*9)/5

= 144 + 9/5 = 145.8

About 146

Choose B.

[Anurag@Gurome]

In a certain animal population, for
each of the first 3 months of life, the
probability that an animal will die
during that month is
1/10 . For a group
of 200 newborn members of the
population, approximately how many
would be expected to survive the first
3 months of life?
(A) 140
(B) 146
(C) 152
(D) 162
(E) 170

Probability of survival for each of the first 3 months of life = 1 - 1/10 = 9/10
So, from a group of 200 newborn members of the population, number expected to survive the first 3 months of life = 200 * 9/10 * 9/10 * 9/10 = 146 approx.

The correct answer is B.